Honestly, and it kinda hurts me to say it, but the belief that blasphemers should be punished is unfortunately a very reasonable interpretation of the Quran. It doesn't take any interpretation at all, it says directly that they should be slain in 33:57-61 for example.
https://en.wikipedia.org/wiki/Islam_and_blasphemy
Don't get me wrong, the Bible commands the death penalty for a lot of things too, like working on a Sunday for example.